(a) Field of the Invention
The present invention relates to a tactual sensor. More particularly, the present invention relates to a tactual sensor using a micro liquid metal droplet.
(b) Description of the Related Art
As an example of a conventional tactual sensor, there is a capacitive tactual sensor. Referring to FIG. 1, the capacitive tactual sensor includes an upper film 2 attached with an upper electrode layer 1 as a portion to be contacted, a lower film 4 attached with a lower electrode layer 3, and an insulating layer 5 provided between the upper electrode layer 1 and the lower electrode layer 3 to separate the contact of the two electrode layers 1 and 3.
As shown in FIG. 2, if a touch force F acts upon the upper film 2, a distance between the two electrode layers 1 and 3 is changed and a capacitance generated between two electrode layers 1 and 3 due to a change of distance therebetween is measured.
However, if the distance between the two electrode layers 1 and 3 is more than 100 μm, the amount of the measured capacitance is very small. Also, since the distance forming a space filled with an air must be maintained to be very small between the two electrode layers 1 and 3, a bending range of the upper film 2 is very small. That is, the capacitive tactual sensor has a very low sensitivity.
Accordingly, the conventional capacitive tactual sensor is suitable for simply determining the contact existence of the portion to be contacted rather than measuring the touch force F acting upon the upper film 2 as the portion to be contacted.
To solve this problem, there is a method of manufacturing a tactual sensor by stacking the capacitive tactual sensor in multiple layers. However, the method of stacking the multiple layers complicates the manufacturing process of the capacitive tactual sensor and deteriorates the manufacturing efficiency.
As another example of the tactual sensor, there is a tactual sensor manufactured by a method of injecting a liquid metal into a micro channel. Since the tactual sensor has a wide cell area, spatial resolution is low, and as the measuring principle is the same as the conventional capacitive tactual sensor, the sensitivity is low and the tactual sensor is not suitable for precision measurement.